As the density of data tracks on magnetic discs continues to increase, increased magnetic efficiency and high manufacturability of the magnetic read/write head, or transducer, is required. Typically, the transducer consists of separate writer and reader elements. One type of writer element is a perpendicular writer. Perpendicular recording, as opposed to the more conventional longitudinal recording, is a form of magnetic recording in which magnetic moments representing bits of data are orientated perpendicularly to the surface of the recording layer of the recording medium. Perpendicular recording offers advantages over longitudinal recording, such as the ability to achieve higher linear densities, which is important to extending disc drive technology beyond current data density limitations.
The reader element is made of multi-layers of magnetic and non-magnetic thin films between which there are magnetic, electrical and physical-chemical interactions. Managing the manufacturing yield and reliability of this complicated structure is becoming increasingly difficult as areal density and head to media spacing becomes smaller. Beyond manufacturing difficulties, the currently designed reader elements depend on the media magnetic flux to rotate the free layer. Consequently, the reader and the shields much be designed so that; a) the media flux reaching the free layer is maximized while b) the shield-shield spacing remains small to maintain bit density. Requirements a) and b) are often conflicting and a compromise must be reached.
Transducers are produced by thin film deposition techniques. In such a process, arrays of transducers are formed on a common substrate or wafer. The wafer is inspected, and is then sliced to produce bars. The bars are then lapped at the surface that will eventually face the recording medium to obtain the desired magnetoresistive element height (also referred to as stripe height). Finally, the bars are diced to form individual sliders, each with a transducer. This conventional process can be problematic for at least two reasons. First, the thin film deposition process is expensive and time consuming. Because of the complexity of depositing multiple layers of different materials, variations can arise between processed wafers, which can result in problems in performance, reliability and predictability. Second, if the lapping process is slightly off, or produces inconsistent magnetoresistive element height, the end product will suffer in performance and in reliability. Other parameters that are considered during the lapping process are metal smearing (corrosion), shorting across the gap (surface finish), pole tip recession and protrusion. Therefore, there is a need for a transducer that can be used for high areal density that is less intricate in terms of the thin film deposition process and the lapping process.
The present invention addresses these and other needs and provides advantages that will become apparent to those skilled in the art.